Bad wirings in baby brains get corrected themselves

Washington: Scientists have identified a protein that plays a vital role in forming the right kind of connections among neuronal cells in the brain of newborn mice, a finding they claim could shed light on neurological disorders such as autism.

In the rapidly developing brain of babies, neurons begin forming connections with one another, but a startling number can link up to the wrong cells and need to be pushed back in the right direction.

Now, researchers at the Biozentrum of the University of Basel discovered that a protein helps neuronal cells in the brain repair errors when they had connected to the wrong type of cells.

The protein called BMP4, a growth factor that controls bone development, was found correcting the initial errors in newborn mice`s cerebellum, an area of the brain that controls fine motor skills and emotional processing.

The researchers, who reported their findings in the journal PLoS Biology, said their work may provide insights into why some young children go on to develop disorders such as autism and schizophrenia.

For their research, the team led by Peter Scheiffele inserted a fluorescent protein into the brains of live unborn mice which was taken up by the neurones and made them glow green under blue light.

This allowed researchers to track how they grew and formed a network during the first three weeks of life.

They found that fibres coming from the cortex often connected and created nerve synapses with the wrong type of cell, called a Purkinje cell, in the cerebellum, when they should have been connecting with granule cells.

But instead of this being a disaster for the growing mouse, those "wrong connections" were soon rectified and being replaced by "correct connections" in a process regulated by the BMP4 protein.

"If inappropriate connections between neurons are not subsequently eliminated, this can lead to substantial disturbances in the brain," said Dr Scheiffele.

"Autism could also be linked to this form of failure to correct errors," he explained.

To test the role of the BMP4 protein, the researchers raised a strain of mouse that lacks the protein and found that the animals subsequently had more "wrong connections", which they could not get rid of.